The results of studies on fish fauna through visual census tehniques carried out in the waters of Portofino promontory since 1991 are reported. Data collected to support the institution of the marine rotected area (MPA), established in 1999, are compared with new information to analyse modifications occuring in fish assemblage species composition. The recorded noticeable fish species richness in the study are allows to positively evaluate the effect of protection thereby giving elements to formulate some biogeographic affinity considerations.